Pipe threading on pipe sections that undergo handling has routinely been protected by thread protectors of steel or other protective materials screwed on the pipe threading. These must be removed before the pipe is coupled to threaded joints. Particularly in the casing pipes used in oil wells, the threaded pipe is expensive and the threads need protection from damage. In this field usual pipe dimensions are 23/8 inches to 24 inches outer diameter.
Problems arise in removal of the thread protectors which may become deformed by impact, etc. in pipe handling. There has been no satisfactory wrench to remove the protectors while assuring that the pipe threads are not damaged in removal by slipping of the wrench or by having to use unorthodox methods of removal because of dirty or damaged thread protectors which require considerable removal torque. Also, it is desirable to reuse the thread protectors, thus requiring removal without damage thereto.
Typical of special pipe wrenches for handling threaded pipes is Sabo--U.S. Pat. No. 3,471,160--Oct. 7, 1969 which requires a special wrench shape mating with slots or keys in the pipe, etc. Such wrenches could not handle standard generally cylindrical pipe thread protectors both for external and internal threads.
In order to preclude the problem aforesaid it has required in the past special expensive pneumatically inflatable thread protectors as set forth for example in U.S. Pat. Nos. Fowler--4,173,988--Nov. 13, 1979; Hauk et al.--4,036,261--July 19, 1977; and Musslewhite--3,858,613--Jan. 7, 1975.
It is, however, an objective of this invention to provide special wrenches overcoming the aforegoing problems, where the wrenches can non-destructively remove simple low cost threaded on thread protectors. Other features, objects and advantages will be found throughout the description, drawing and claims.